Combustion apparatus for both gaseous and non-gaseous fuels



Feb. 22, 1966 F. BEYER 3,236,279

COMBUSTION APPARATUS FOR BOTH GASEOUS AND NON-GASEOUS FUELS Filed Oct.2, 1961 2 Sheets-Sheet 1 I8 H I? 10 I4 20 22 ll l4 10 INUENTOK FzAuKQEaQ ATTOR Y F. BEYER Feb. 22, 196$ COMBUSTION APPARATUS FOR BOTH GASEOUSAND NON-GASEOUS FUELS 2 Sheets-Sheet 2 Filed Oct. 2, 1961 INWSNTIE FRANKB R 5 mm;

fi-rrvreucrv United States Patent 3,236,279 COMBUdTIQN APPARATUS FORBOTH GASEOUS AND N ON -GASE )US FUELS Frank Beyer, Leitershofen,Augsburg, Germany, assignor to Maschinenfabrik Augsburg-Nurnberg A.G., acorporation of Germany Filed Oct. 2, 1961, Ser. No. 142,275 Claimspriority, application Germany, Oct. 7, 1969, M 46,763 12 Claims. (Cl.15Sl1) This invention relates to combustion devices or burner apparatusfor furnaces, gas turbine combustion chambers, and the like, forutilizing, simultaneously or alternatively, both gaseous and non-gaseousfuels and, more particularly, to such multiple fuel burner constructionsfor gas turbine combustion chambers using oil and gaseous fuels.

In various combustion devices for providing combustion or reacting heatfor various heating or reaction furnaces and combustion chambers and thelike, it may be desired to utilize a burner structure capable ofaccommodating, simultaneously or alternatively, different types of fuelssuch as for example, a liquid oil fuel and a gaseous fuel. Thus, amultiple fuel burner arrangement may be desired to operate generally byburning a gaseous fuel, but including means whereby an oil burner may bereadily placed in operation as, for example, should the supply ofgaseous fuel fail or diminish below operating levels, As will beunderstood, such a device may incorporate generally a gas burnerarrangement in which a gaseous fuel and primary combustion air areadmixed to form a combustible mixture for burning in the combustionspace and also an oil burner device in which liquid fuel and primarycombustion air are admixed as a combustible jet or stream for injectioninto the combustion space. In such a device, it may be desired to havethe oil burner apparatus and the gas burner apparatus arranged togetherso that, for example, the flame originates at generally the same pointin the combustion chamber regardless of which type of fuel is beingused, and, if so, the construction may be complicated by having one orthe other of the burners displaceable and/or constructed of specialheat-resistant materials so as to avoid or withstand direct or closecontact with the hot flame produced by the other burner.

In any event, if it is attempted to utilize different types of gaseousand non-gaseous fuels, having different heat contents or values, in aunitary multiple fuel burner device, some difficulty may be experiencedfrom the fact that such different types of fuels may require foroptimumly efiicient use widely varying quantities and velocties andproportions of primary combustion air for admixture therewith.Furthermore, such difliculties may arise with installations such as gasturbine combustion chambers where it is also desired to throttle or varythe amount of fuel being burned at various times, as under partial loadoperation, which variations require additional variation in the amountof primary air introduced through the burners.

For example, considerations of the pertinent pyrotechnics and fluiddynamics indicate widely varying and even inconsistent conditions ofprimary air supply for achieving optimum combustion efficiency orsatisfactory operation with different types and varieties of fuels. Agaseous fuel such as blast furnace gas of low heat value may requirerelatively low velocities of both fuel and primary air, whilesatisfactory results with a non-gaseous fuel such as coal tar oil may beobtained only with much higher velocities for primary air supplied to orthrough a jet-type oil burner. Particularly with installations Where therequirement for providing such widely differing velocity and supplyconditions for the primary air for dilferent fuels is furthercomplicated by the additional desire of also altering from time to timethe amount or rate of both or either fuel supplied for combustion,difliculty or even impossibility may be experienced in attempting todesign or provide air-fuel mixing arrangements providing both theinconsistent characteristics of large volume low velocity flow for onefuel and high velocity or variable flow for the other fuel in the sameburner construction or from a single supply of primary air.

Thus, with a substantially constant quantity or pressure of primary airand without some special extra control, the large aggregate flowcross-sectional areas of alternate gas and air mixing ports for a gasburner may not offer enough throttling resistance to provide alsodesirably low air velocities for reduced or throttled operation, while,alternatively, if the primary air supply is redesigned to accommodatethe foregoing considerations for throttled gas fuel operation, they maybe inadequate for simultaneously or alternatively supplying suflicientquantities of high velocity air for satisfactory oil burner operation.

According to this invention, however, multiple fuel combustion apparatusis provided for accommodating or obviating the foregoing diflicultiesand inconsistent operating requirements not only for different types offuel but also for operation at different consumption rates, as for fullload and partial load operation, whereby the air discharge grid oraperture of the oil burner assures greater flow velocities than the airmixing ports of the gas burner and, accordingly, is provided with asubstantially smaller effective air discharge cross-section than that ofthe gas burner; and a simple control element is provided for throttlingor controlling the feed of primary air to one or both gas andnon-gaseous burners for achieving optimum or satisfactory air supply andoperating conditions in each notwithstanding the varying requirements ofair supply and flow velocities for the different types of fuels. As afurther feature of this invention such correlation of air dischargecross-sections for the gas burner and oil burner provide, at least forfull load operation, sufiicient throttling action and velocity controlso that a separate air throttling member for air supply to the oilburner may normally be dispensed with, although such control is simplyprovided in accordance herewith for partial load operation; and thethrottling control for primary air supplied to the gas burner includesprovision of a small cooling air flow thereto during operation of theoil burner even when the gas burner is not operating; and, in accordanceherewith, a construction is provided whereby both the oil burner and thegas burner are permanently oriented with respect to each other and inorder to avoid undesired heating effects on either by direct impingementof flames from the other without requiring displacement of one withrespect to the other or the use of special heat-resistant materialstherefor.

With the foregoing and other objects in mind, this invention will now bedescribed in more detail, and other objects and advantages thereof willbe apparent from the following description, the accompanying drawings,and the appended claims.

In the drawing:

FIG. 1 is an axial section through a multiple fuel burner constructionembodying and for practicing this invention and as mounted in acombustion chamber of a gas turbine;

FIG. 2 is a fragmentary view in elevation of a portion of the primaryair flow control member of FIG. 1; and

FIG. 3 is a partial axial section through a combustion chamber havingmounted therein a plurality of multiple fuel burner devices embodyingand for practicing this invention and indicating a modification ofcontrol of primary air flow in accordance herewith.

Although it is to be understood that apparatus embodying and forpracticing this invention is satisfactorily applicable to a wide varietyof furnace and combustion chamber constructions for accommodating a widevariety of different fuels, the following description relates, purelyfor illustrative purposes, to a gas turbine combustion arrangement forutilizing ordinary blast furnace gas and coal tar oil as, respectively,the gaseous and non-gaseous fuels for providing simultaneously oralternatively the desired combustion heat. Thus, referring to thedrawings, in which like reference characters refer to like partsthroughout the several views thereof, there is shown in FIG. 1 such amultiple fuel burner construction in accordance herewith and mountedthrough the end wall of a combustion chamber which encloses a combustionspace 11 into which the flames of the illustrated device are directed.The multiple burner construction, indicated generally by 12, issurrounded by a supply or storage space 13 for primary combustion air,and is mounted in an opening in Wall 10 as by frame or casing 14.

The oil burner portion of the illustrated combustion device is indicatedgenerally by 15 and comprises an oil injection nozzle assembly 16,supplied with fuel oil through the lower end 16a thereof, mountedcentrally within a large pipe or air conduit 17, across the upper ordischarge end of which is provided an air swirl grid 18, through whichprimary combustion air is discharged from pipe 17 into combustion space11 and to form a combustible mixture therein with spray droplets of fueloil being injected from the upper or discharge end of oil nozzle 16, allin known manner.

The gas burner portion of the illustrated structure is indicatedgenerally by 211 as comprising a ring of alternating air discharge ports21 and gas discharge ports 22 forming a burner ring around oil burner 15and with the ports 21 and 22 being formed as elongated slots and beingdisposed to discharge air and gas into combustion space 11 and at anangle to the axis of burner construction 12 for forming a combustiblemixture, in known manner fuel gas is supplied through pipes 25 into anannular gas channel or conduit 25, and flows therethrough upwardly andout the various gas ports 22. Primary combustion air for burning thegaseous fuel enters the combustion device from storage space 13 througha plurality of openings 27, each of which communicates with an airdischarge port 21 in the gas burner ring to form thereat a combustiblemixture with gas from gas ports 22. Primary combustion air for the oilburner 15 enters the device from air space 13 through a plurality ofradial conduits or channels 31 which traverse the annular gas conduit 26and conduct air from storage space 13 into the pipe or conduit 17 of oilburner 15. Throughout the drawings, the flow of gaseous fuel isindicated by solidline arrows, while the fiow of primary combustion airis indicated by dotted-line arrows.

An annular ignition gas burner 35 is provided around the innercircumference of gas burner ring 20 and outside oil burner 15 for use inigniting the device in the first place, which ignition burner 35 issupplied with an ignitable gas-air mixture supplied through pipe 36 intochamber 37 and through conduit 38, traversing annular gas channel 25,into an annular conduit 39 leading to ignition burner 35.

As will be apparent from the foregoing, fuel gas and fuel oil areseparately supplied, through pipes and 16, to oil burner 15 and gasburner 20. Primary air, from a source 13 thereof under substantiallyconstant pressure, is separately supplied through conduits to oil burner15 and through openings 27 to air ports 21 of gas burner 20. In such anarrangement, even for full load operation and particularly where a highheat production is demanded of the combustion chamber and the airstorage space 13 is supplied under substantial pressure as with gasturbines, quite different quantities and flow rates of primarycombustion air are required for optimumly efficient operation of oilburner 15 and gas burner 20, and such varied conditions of primary airsupply are accommodated in accordance herewith by providing differenteffective discharge cross-sections for primary air passing through grid18 of oil burner 15 as compared with the effective dischargecross-sections of air discharge ports 21 in gas burner ring 20. Thus,the discharge cross-section of grid 18 is controlled by combined factorssuch as the internal diameter of conduit 17 and the height spacing andoblique angle of the various blades or partitions forming grid 18, aswell known. The discharge cross-section of air ports 21 in gas burner 20is controlled by the radial extension 11 (FIG. 1) and the width a (FIG.2) thereof.

In accordance herewith, then, substantially higher discharge velocitiesare desired for the primary air passing through grid 18 of oil burner 15to form a combustible mixture with droplets of oil fuel injected fromnozzle 16, so grid 18 is provided with a substantially smaller effectivedischarge cross-section than that of air ports 21 in gas burner 25. Aswill be understood, the respective optimum flow velocities desired forthe supplies of primary air to achieve desired combustioncharacteristics are readily determined or calculated with respect tovarious types of gaseous and non-gaseous fuels being used, and with dueregard to the air pressure in air reservoir 13 and the relatively highflow velocities to be induced thereby. As illustrative, for the fuelsblast furnace gas and coal tar oil, satisfactory results are obtainedwhen the discharge velocity of primary air out of grid 18 intocombustion space 11 is about five times the discharge velocity ofprimary air out of air ports 21 in gas burner 20, and, accordingly, thecross-section and construction of grid 18 is provided, with respect tothat of air ports 21, so as to maintain approximately such ratio of airvelocities, at least for full load (i.e., unthrottled) operation of thedevice.

There is also indicated in FIGS. 1 and 2 a control member forcontrolling or throttling the supply of primary air from air reservoir13, which member is indicated as a movable sleeve 45 surrounding thedevice and mounted for rotation therearound as by hearings or rollers46. An internally toothed ring 47 is provided near the bottom of sleeve45 with a gear 48 in meshing engagement therewith and mounted forrotation on a control shaft 49 whereby, as will be understood, rotationof shaft 49 and gear 43 thereon causes the entire sleeve 45 to revolvearound the outside of the burner construction. A plurality of slots 55are provided in sleeve 45 for coinciding with openings 27 leading fromair space 13 to various air ports 21 in burner ring 20, so that, assleeve 45 is rotated, slots 55 will selectively open or close openings27 for controlling the flow of air therethrough from air space 13.Similarly a plurality of openings 56 are also provided in sleeve 45 forcoinciding with or closing off the outer ends of channels 30 tointerrupt or control the flow of primary air therethrough from air space13 to oil burner 15 depending upon the angular positioning of sleeve 45.Furthermore, the situation illustrated in FIG.- 2 indicates theplacement of slots 55 and openings 56 with respect to the air admissionopenings 27 and 30 to provide for operation of gas burner 20 only whenoil burner 15 is not operating and vice versa, although, as Will beunderstood, other operating conditions are satisfactorily provided inaccordance herewith.

In order to protect gas burner 20 from the undesired heating effects ofoil burner 15 when the latter is in operation, the discharge end of oilnozzle 15 and pipe 17 of oil burner 15 preferably extend axially fromsome distance beyond gas burner 20 into the combustion space 11 so as toavoid direct impingement of the flame from oil burner 15 on gas burnerring 20. Additionally, as indicated in FIG. 2, the width of slots 55 insleeve 45 and the solid width b in the sleeve between slots 55 arepreferably correlated so that, even when sleeve 45 is in an angularposition closing openings 27 to the greatest possible extent, as duringoperation of oil burner E) 15, still there will be a little open areathrough slots 55 and openings 27 for leakage or passage of sufiicientair from storage space 13 through air ports 21 to maintain a coolingeffect on gas burner 20 even when there is no flow of gas through gasports 22. In this manner, the gas burner 20 can be satisfactorilyconstructed of ordinary sheet metal without the extra expense ordifiiculty of providing high heat resistance to withstand heating by oilburner 15 during operation thereof.

A further modification of structures embodying and for practicing thisinvention is indicated in FIG. 3 as a combustion device 60 including acombustion chamber 61 having mounted in the bottom 62 thereof aplurality of symmetrically arranged multiple fuel burners 63 inaccordance herewith. Each of the burner constructions 63 is generallysimilar to that described above and includes an oil burner 65 with oilnozzle 66 and air discharge grid 67, as well as a gas burner ringarrangement 68 having alternate fuel gas and air ports as previouslydescribed. Oil fuel is supplied to nozzle 66 of oil burner 65 throughoil pipe 70, and gaseous fuel is supplied to gas burner 68 through pipe71 into an annular conduit or manifold 72, corresponding generally toannular conduit 26 in FIG. 1, and thence to the gas ports of gas burner68 substantially as described with respect to FIG. 1. Primary air entersoil burner 65 through radial conduits 3t), and also is led to air portsof gas burner 68 through openings 27 as previously described.

In the construction of FIG. 3, the space within the outer casing ofcombustion apparatus 60 and below or outside combustion chamber 61therein forms a supply reservoir 75 for primary combustion air suppliedthereinto under pressure through conduit 76. Also air reservoir 75 isdivided into two chambers 77 and 78 by a transverse partition 79 havinga central opening 8i) therein, which opening is controlled by a mushroomvalve 81 operated as by a control rod 82 in known manner.

As will be understood from the foregoing, upper air chamber 78 abovepartition 79 communicates with openings 27 supplying primary air to gasburner 68, while lower air chamber '77 below partition 79 communicateswith channels 36 supplying primary air to oil burner 65. Also, since allthe primary air is initially supplied to reservoir 75 through pipe 76below partition '79, the amount of air available for flow throughopenings 27 to gas burner 68 from upper chamber 78 is under the con trolof valve 81. Accordingly, during operation in which both gas and oilburners are used, the flow of primary air to gas burner 68 is under thecontrol of mushroom valve 81 independently of any throttling of air fromchamber 77 to oil burner 65 and, of course, in addition to the dischargeflow ratios provided by correlating the discharge cross-section grid 67of oil burner 55 with that of the air ports in gas burner 68. Similarly,in the case where operation is conducted solely by oil burner 65 andwith fuel gas shut off in pipe 71 to gas burner 68, valve 81 is closedbut not quite completely so as to provide some leakage through opening8&3 in partition 79 of air to gas burner 68 for the above noted coolingeffect thereof during operation of oil burner 65.

As will be apparent from the foregoing, there is provided according tothis invention multiple fuel burner apparatus for use in a variety offurnaces or combustion chambers for the simultaneous or alternativecombustion of various types of gaseous and non-gaseous fuels to provideheat for a wide variety of furnaces and combustion chambers and devicesas may be used in industry, for metallurgical purposes, in chemicalprocessing, coke oven plants, oil recovery, and similar operations, butparticularly adapted to combustion chambers for gas turbines and similarapplications where primary combustion air is supplied under pressure andwith fairly high flow velocities and/ or where optimum efficiency isdesired for both full load and partial load operation with either orboth of two different kinds of fuels. Furthermore, there is provided aconstruction for accommodating and controlling the different flow ratesand quantities of primary air desired from a single source thereof toprovide optimum operating conditions notwithstanding the fact that thegaseous and non-gaseous fuels demandwidely different air discharge flowrates and velocities and quantities for efiicient combustion.

Similarly, there is provided in accordance herewith such a multiple fuelburner apparatus as a substantially integrated and self-contained unitfor mounting in a combustion chamber or other type of fire box orfurnace, and including air throttling controls of extremely simpleconstruction and operation, while the respective orientation of theburners for gaseous and non-gaseous fuels are arranged to avoid orobviate undesired or excessive heating of one burner during theoperation of the other, and with the provision of cooling air flowthrough the gas burner even when it is not operating and during theoperation of the burner for liquid or non-gaseous fuel, and withseparate throttling control of combustion air to each or both of the twoburners and/or for accommodating or selecting either simultaneous oralternative operation thereof While the forms of apparatus hereindescribed constitute a preferred embodiment of the invention, it is tobe understood that the invention is not limited to these precise formsof apparatus, that changes may be made therein Without departing fromthe scope of the invention which is defined in the appended claims.

What is claimed is:

1. In a multiple fuel combustion device of the character describedhaving separate gaseous fuel and non-gaseous fuel burners arrangedtogether for discharging said fuels and combustion air into a combustionspace for the mixing thereof and substantially complete combustiontherein with an excess of air, said different fuels requiring differentvelocities and proportions of combustion air, the combination whichcomprises means providing a single source of air supply under pressurefor both said gaseous and non-gaseous fuel burners for admixture withsaid fuels and including an excess amount of air for providing forsubstantially complete combustion of said fuels, air discharge means insaid non-gaseous fuel burner for discharging air with said non-gaseousfuel into a combustion space for mixing and substantially completecombustion therein, separate and independent air discharge means in saidgaseous fuel burner for discharging air with said gaseous fuel into saidcombustion space for mixing and substantially complete combustiontherein, said gaseous fuel burner being disposed as a ring ofalternating air and fuel ports around said non-gaseous fuel burner, saidair discharge means in said non-gaseous fuel burner having asubstantially smaller effective cross-sectional area than said airdischarge means in said gaseous fuel burner for providing substantiallyhigher air discharge velocities than said gaseous fuel burner,adjustable air control means for throttling the flow of air from saidsource of air supply to said gaseous fuel burner and concomitantlycontrolling said flow of air to said non-gaseous fuel burner, and meansin said air control means for maintaining a small cooling flow of air tosaid gaseous fuel burner even in the fully throttled position of saidcontrol means and when said gaseous fuel burner is not operating forproviding cooling thereof from the heat of said non-gaseous fuel burner.

2. A multiple fuel combustion device as recited in claim 1 in which saidmeans providing a source of air supply under pressure for both saidgaseous and non-gaseous fuel burners includes separate air reservoirs inflow communication separately with said gaseous and non-gaseous fuelburners, means for providing air under pressure into the one of saidreservoirs which is in flow communication with said non-gaseous fuelburner, and means providing flow communication between said reservoirs,said adjustable air control means controlling the flow of air from saidreservoir in communication with said non-gaseous fuel burner into saidreservoir in communication with said gaseous fuel burner.

3. A multiple fuel combustion device as recited in claim 2 in which saidair control means includes a valve controlling flow of air between saidseparate air supply reser- VOlIS.

4. A multiple fuel combustion device as recited in claim 3 in which saidvalve includes means for maintaining a small cooling flow of air fromsaid non-gaseous fuel air reservoir into said gaseous fuel air reservoireven in the closed position of said valve for providing a cooling flowof air to said gaseous fuel burner even when said burner is notoperating.

5. A multiple fuel combustion device as recited in claim 3 in which aplurality of said gaseous fuel and non-gaseous fuel burners are mountedfor discharging said combustible fuel-air mixtures into said combustionspace at various points thereacross, and in which one of said air supplyreservoirs is in flow communication with all of said gaseous fuelburners and the other of said air supply reservoirs is in flowcommunication with all of said non-gaseous fuel burners, whereby saidcontrol of said air supply to said gaseous fuel burner air reservoirsimultaneously effects control of the air supply to all said gaseousfuel burners.

6. In a multiple fuel combustion device of the character describedhaving separate gaseous fuel and nongaseous fuel burners arrangedtogether for discharging said fuels and combustion air into a combustionspace for the mixing thereof and substantially complete combustiontherein with an excess of air, said different fuels requiring differentvelocities and proportions of combustion air, the combination whichcomprises means providing a single source of air supply under pressurefor both said gaseous and non-gaseous fuel burners for admixture withsaid fuels and including an excess amount of air for providing forsubstantially complete combustion of said fuels, separate means in eachof said burners for discharging air for admixture with said fuels, saidair discharge means in said non-gaseous fuel burner having asubstantially smaller effective cross-sectional discharge area than saidair discharge means in said gaseous fuel burner for accommodatingsubstantially higher air discharge velocities than said gaseous fuelburner and being disposed in spaced relation to said non-gaseous fuelburner sufficiently to have substantially no effect upon the air fuelratio discharge therefrom, single adjustable air control means forthrottling the flow of air from said single source of air supply to saidgaseous fuel burner and concomitantly controlling the flow of air fromsaid source to said non-gaseous fuel burner, and means in said aircontrol means for maintaining a small cooling flow of air to saidgaseous fuel burner even in the fully throttled position thereof andwhen said gaseous fuel burner is not operating for providing coolingthereof from the heat of said non-gaseous fuel burner.

7. A multiple fuel combustion device as recited in claim 6 in which saidadjustable air control means for said gaseous fuel and said non-gaseousfuel burners is a rotating valve sleeve interposed between said burnersand said source of supply of air therefor.

8. A multiple fuel combustion device as recited in claim 7 in which saidrotating valve sleeve includes separate air admission aperturesintermittently disposed therearound for providing flow of air from saidsource of air supply separately to said gaseous and non-gaseous burners,and in which said intermittent air admission apertures are disposed onsaid valve sleeve to overlap at certain predetermined positions of saidsleeve to control flow of air to said burners for selectivelydetermining the alternative and simultaneous operation thereof.

9. In a multiple fuel combustion device of the character describedhaving separate gaseous fuel and nongaseous fuel burners arrangedtogether for discharging said fuels and combustion air into a combustionspace for the mixing thereof and substantially complete combustiontherein with an excess of air, said different fuels requiring differentvelocities and proportions of combustion air, the combination whichcomprises means providing a source of air supply under pressure for bothsaid gaseous and non-gaseous fuel burners for admixture with said fuelsand including an excess amount of air for providing for substantiallycomplete combustion of said fuels, separate and independent means ateach of said burners for discharging air for admixture with said fuelsseparately at each of said burners for independently forming fuel-airmixtures, said air discharge means in said non-gaseous fuel burnerhaving a smaller effective cross-sectional discharge area than said airdischarge means in said gaseous fuel burner for providing higher airdischarge velocities than said gaseous fuel burner and including an airswirl grid through which said air is discharged for mixture with anon-gaseous fuel in a combustion space, said gaseous fuel burner beingdisposed as a ring of alternating fuel and air slots positioned radiallyand at an acute angle around said non-gaseous fuel 'burner, saidnon-gaseous fuel burner extending into said combustion space axiallybeyond said gaseous fuel burner for discharging said air and non-gaseousfuel for mixing and combustion therein at a point spaced from saidgaseous fuel burner for avoiding direct impingement of said non-gaseousfuel combustion on said gaseous fuel burner, single adjustable aircontrol means for throttling the flow of air from said source of airsupply to said gaseous fuel burner and concomitantly controlling theflow of air to said non-gaseous fuel burner, and means in said aircontrol means for maintaining a small cooling flow of air to saidgaseous fuel burner even in the fully throttle position of said aircontrol means.

10. A multiple fuel combustion device as recited in claim 9 whichadditionally comprises an igniting burner device disposed between saidnon-gaseous fuel burner and said gaseous fuel burner, and means forsupplying a combustible fuel mixture to said igniting burner sepa ratelyfrom said fuel and air supplied to said gaseous fuel and non-gaseousfuel burners.

11. In a multiple fuel combustion device of the character describedhaving separate gaseous fuel and nongaseous fuel burners arrangedtogether for discharging said fuels and combustion air into a combustionspace for the mixing thereof and substantially complete combustiontherein with an excess of air, said different fuels requiring differentvelocities and proportions of combustion air, the combination whichcomprises means providing a source of air under pressure for supplyingair to both said gaseous and non-gaseous fuel burners for admixture withsaid fuels separately to form fuel-air mixtures for substantiallycomplete combustion in a combustion space, air discharge means in saidgaseous fuel burner for discharging air to form said combustible mixtureWith said gaseous fuel, separate air discharge means in said non-gaseousfuel burner having a substantially smaller effective cross-sectionaldischarge area than said air discharge means in said gaseous fuel burnerproviding a substantially higher air discharge velocity of about fivetimes that of said air discharge at said gaseous fuel burner, andadjustable air control means for throttling the flows of air from saidsource of air supply to said gaseous fuel burner and including means formaintaining a small cooling flow of air to said gaseous fuel burner evenin the fully throttled position of said air control means for coolingsaid gaseous fuel burner during operation of said non-gaseous fuelburner.

12. In a multiple fuel combustion device of the character describedhaving gaseous fuel and non-gaseous fuel burners coaxially arranged todischarge separate fuels and air into a combustion chamber forsubstantially complete mixture and combustion therein and with separatedischarges including substantially different excesses of air, saiddevice being mounted in awall of said combustion chamber, thecombination which comprises means comprising a source of air supply forsaid gaseous and non-gaseous fuel burners for admixture with said fuelsseparately to form separate combustible fuel-air mixtures, separate airejection and admixing means in each of said burners for discharging saidseparate combustible fuels and air for admixture in said combustionchamber, said air ejection and admixing means in said non-gaseous fuelburner having a substantially smaller air ejecting crosssectional areathan said air ejection and admixing means in said gaseous fuel burnerfor accommodating substantially higher air ejection and dischargevelocity than said gaseous fuel burner and including an air swirl gridthrough which said fuel-air mixture is discharged into said combustionchamber, with said air ejection and admixing means for said gaseous fuelburner including a ring of alternative fuel and air slots disposedradially around said non-gaseous fuel burner and at an acute angle tothe axis thereof, adjustable air control means for adjusting the flow ofair from said source of air supply to said gaseous fuel burner, meansfor maintaining a small cooling flow of air to said gaseous fuel burnerproviding cooling thereof from heat from said nongaseo lsfuel burnerwhen said gaseous fuel burner References Cited by the Examiner UNITEDSTATES PATENTS 1,428,574 9/1922 Woolley 1581.5 1,647,675 11/ 1927 Vedder110-22 1,687,390 10/ 1928 Ritter 15'811 1,731,722 10/1929 Meier 158991,736,345 11/1929 Hopkins 12811 2,458,542 1/1949 Urquhart 158112,851,093 9/1958 Zink et al. 15811 FREDERICK L. MATTESON, JR, PrimaryExaminer.

MEYER PERLIN, JAMES W. WESTHAVER,

Examiners.

1. IN A MULTIPLE FUEL COMBUSTION DEVICE OF THE CHARACTER DESCRIBEDHAVING SEPARATE GASEOUS FUEL AND NON-GASEOUS FUEL BURNERS ARRANGEDTOGETHER FOR DISCHARGING SAID FUELS AND COMBUSTION AIR INTO A COMBUSTIONSPACE FOR THE MIXING THEREOF AND SUBSTANTIALLY COMPLETE COMBUSIONTHEREIN WITH AN EXCESS OF AIR, SAID DIFFERENT FUELS REQUIRING DIFFERENTVELOCITIES AND PROPORTIONS OF COMBUSTION AIR, THE COMBINATION WHICHCOMPRISES MEANS PROVIDING A SINGLE SOURCE OF AIR SUPPLY UNDER PRESSUREFOR BOTH SAID GASEOUS AND NON-GASEOUS FUEL BURNERS FOR ADMIXTURE WITHSAID FUELS AND INCLUDING AN EXCESS AMOUNT OF AIR FOR PROVIDING FORSUBSTANTIALLY COMPLETE COMBUSTION OF SAID FUELS, AIR DISCHARGE MEANS INSAID NON-GASEOUS FUEL BURNER FOR DISCHARGING AIR WITH SAID NON-GASEOUSFUEL INTO A COMBUSTION SPACE FOR MIXING AND SUBSTANTIALLAY COMPLETECOMBUSTION THEREIN, SEPARATE AND INDEPENDENT AIR DISCHARGE MEANS IN SAIDGASEOUS FUEL BURNER FOR DISCHARGING AIR WITH SAID GASEOUS FUEL INTO SAIDCOMBUSTION SPACE FOR MIXING AND SUBSTANTIALLY COMPLETE COMBUSTIONTHEREIN, SAID GASEOUS FUEL BURNER BEING DISPOSED AS A RING OFALTERNATING AIR AND FUEL PORTS AROUND SAID NON-GASEOUS FUEL BURNER, SAIDAIR DISCHARGE MEANS IN SAID NON-GASEOUS FUEL BURNER HAVING ASUBSTANTIALLY SMALLER EFFECTIVE CROSS-SECTIONAL AREA THAN SAID AIRDISCHARGE MEANS IN SAID GASEOUS FUEL BURNER FOR PROVIDING SUBSTANTIALLYHIGHER AIR DISCHARGE VELOCITIES THAN SAID GASEOOUS FUEL BURNER,ADJUSTABLE AIR CONTROL MEANS FOR THROTTLING THE FLOW OF AIR FROM SAIDSOURCE OF AIR SUPPLY TO SAID GASEOUS FUEL BURNER AND CONCOMITANTLYCONTROLLING SAID FLOW OF AIR TO SAID NON-GASEOUS FUEL BURNER, AND MEANSIN SAID AIR CONTROL MEANS FOR MAINTAINING A SMALL COOLING FLOW OF AIR TOSAID GASEOUS FUEL BURNER EVEN IN THE FULLY THROTTLED POSITION OF SAIDCONTROL MEANS AND WHEN SAID GASEOUS FUEL BURNER IS NOT OPERATING FORPROVIDING COOLING THEREOF FROM THE HEAT OF SAID NON-GASEOUS FUEL BURNER.